1. Field of the Invention
The present invention relates to vacuum cleaners, and more particularly to canister vacuum cleaners with cartridge filters that need occasional cleaning.
2. Description of Related Art
The familiar canister vacuum cleaner, or shop vac, is a common appliance in many American homes and workshops. The most popular designs place a vacuum pump and electrical motor on top of a canister lid. A cartridge filter is held underneath the lid and the vacuum pump draws air through the filter and out to an exhaust. The whole assembly on the lid is then latched to the top of a canister bucket and a vacuum hose is attached to the side. Any debris that is drawn in through the hose drops inside the bucket and is prevented from passing through by the cartridge filter.
Fine particles which are not heavy enough to drop to the bottom of the bucket will lodge and cake on the filter. Such filters are typically made of pleated paper and a lot of the sweepings will trap between the pleats. The paper matrix itself will also clog. So, over time, the cartridge filter will eventually become so clogged that no vacuum air can be drawn through.
Users typically dump the contents of the canister bucket and shake the loose material out of the cartridge filter. This can be very messy and the filter does not really come very clean. Thus the filter cartridges need to be replaced frequently. Some users simply replace the filter on every cleaning to avoid the mess associated with beating or shaking the old filters free of dirt.
The present inventor, David E. Dudley, describes the cleaning of water filter cartridges in two previous patents by spinning the filter cartridges to take advantage of centrifugal force. U.S. Pat. No. 5,989,419, issued Nov. 23, 1999, describes a spinner on which a dirty, removable pool filter can be mounted. A water jet from a hose is directed at the filter and it will spin on its own on the axle provided. The combination of the water jet and spinning of the filter causes filter cake to be washed and flung free. U.S. Pat. No. 6,156,213, issued Dec. 5, 2000, describes an in-situ spin-clean water filter. An enclosed filter is mounted on a pivot so it can easily spin but not allow internal water-bypass leakage. Strategically placed water jets inside can be turned on to cause the filter to be spun, e.g., after the enclosure has been drained. Both such Patents are incorporated herein by reference.
Briefly, a method embodiment of the present invention comprises mounting a cylindrical-shaped filter cartridge coaxially on a rotatable spindle. Air is then drawn radially through a filter material wall of the filter cartridge during normal operation, as in a vacuum cleaner. Periodically, the cartridge filter on the spindle is spun to dislodge any debris entrapped in the filter material by centrifugal force. An air flow control can be included to selectively draw or push air radially through a filter material wall of the filter cartridge. A clutch disposed between a motor and the spindle may be used to spin the cartridge filter.
An advantage of the present invention is a shop vac is provided that can be easily cleaned.
Another advantage of the present invention is that a filter system is provided that allows filter cartridges to be reused.
A still further advantage of the present invention is that a method is provided for automatically maintaining a vacuum cleaning system.
The above and still further objects, features, and advantages of the present invention will become apparent upon consideration of the following detailed description of specific embodiments thereof, especially when taken in conjunction with the accompanying drawings.